Paraquat and Parkinson's disease: an overview of the epidemiology and a review of two recent studies

Regul Toxicol Pharmacol. 2012 Mar;62(2):385-92. doi: 10.1016/j.yrtph.2011.10.004. Epub 2011 Oct 15.


Objective: This paper reviews and evaluates two recent epidemiologic studies focused on pesticides, and in particular, paraquat as a cause of PD. Both studies are derived primarily from the Agricultural Health Study (AHS). A review and evaluation is also provided on the AHS and several additional studies of paraquat and PD.

Methods: The methods used to design and conduct the studies and analyze the data are described and evaluated.

Results: Studies were inadequately designed and often underpowered with very few exposed individuals. They were not population-based, failed to distinguish incident from prevalent cases, relied on multiple comparisons, and may have reported results selectively. The results across the studies are inconsistent.

Conclusions: The inherent difficulties of studying Parkinson's disease in relation to paraquat or other pesticides are well illustrated by these studies. A conclusion regarding these relationships cannot be reached based on the current literature. Further research with higher methodological standards is needed to reach a definitive conclusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Case-Control Studies
  • Herbicides / toxicity*
  • Paraquat / toxicity*
  • Parkinson Disease / epidemiology
  • Parkinson Disease / etiology*
  • Pesticides / toxicity


  • Herbicides
  • Pesticides
  • Paraquat